The proposal is to interview a subsample of about 400 from a representative sample of young men, age 20-30 when they were first interviewed in 1974-75, with primary emphasis on marihuana use. Goals are to look for effects, including health effects, of years of intensive marihuana use. Other goals are to relate changes in patterns of drug use (here including use of other drugs) to life events, such as marriage, fatherhood, job promotion, job losses, arrests, and so on, with the assumption that the causal direction in such relationship, if it is causal, could be in either direction. A by-product will be to study the reliability of survey data, by repeating some items from the original interviews exactly.